Temporal lobe interictal spikes disrupt encoding and retrieval of verbal memory: A subregion analysis.

OBJECTIVE: The medial temporal lobe (MTL) encodes and recalls memories and can be a predominant site for interictal spikes (IS) in patients with focal epilepsy. It is unclear whether memory deficits are due to IS in the MTL producing a transient decline. Here, we investigated whether IS in the MTL subregions and lateral temporal cortex impact episodic memory encoding and recall. METHODS: Seventy-eight participants undergoing presurgical evaluation for medically refractory focal epilepsy with depth electrodes placed in the temporal lobe participated in a verbal free recall task. IS were manually annotated during the pre-encoding, encoding, and recall epochs. We examined the effect of IS on word recall using mixed-effects logistic regression. RESULTS: IS in the left hippocampus (odds ratio [OR] = .73, 95% confidence interval [CI] = .63-.84, p < .001) and left middle temporal gyrus (OR = .46, 95% CI = .27-.78, p < .05) during word encoding decreased subsequent recall performance. Within the left hippocampus, this effect was specific for area CA1 (OR = .76, 95% CI = .66-.88, p < .01) and dentate gyrus (OR = .74, 95% CI = .62-.89, p < .05). IS in other MTL subregions or inferior and superior temporal gyrus and IS occurring during the prestimulus window did not affect word encoding (p > .05). IS during retrieval in right hippocampal (OR = .22, 95% CI = .08-.63, p = .01) and parahippocampal regions (OR = .24, 95% CI = .07-.8, p < .05) reduced the probability of recalling a word. SIGNIFICANCE: IS in medial and lateral temporal cortex contribute to transient memory decline during verbal episodic memory.

Emergency department visits and readmissions in patients with psychogenic nonepileptic seizures (PNES) at a safety net hospital.

INTRODUCTION: Readmissions and emergency department (ED) visits after an index admission have been become a quality measure due to associations with poor outcomes and increased healthcare costs. Readmissions and ED encounters have been studied in a variety of conditions including epilepsy but have not been examined exclusively in psychogenic nonepileptic seizures (PNES). In this study we examined the rate of readmissions and ED visits after a discharge from an Epilepsy Monitoring Unit (EMU) in a safety net hospital. We also determined patient phenotypes that are associated with readmissions. MATERIAL AND METHODS: This was a retrospective chart review study with index admission being a discharge from an EMU between January 1 and December 31 2016 with follow-up until August 31 2020. We obtained data regarding demographics, medical and psychiatric history, and social history and treatment interventions. Our outcome variables were both all-cause and seizure-related hospital readmissions and ED visits 30 days following the index discharge and readmissions and ED visits 30 days thereafter. RESULTS: Eleven of 122 patients (9%) had a non-seizure-related ED visit and/or hospitalization within 30 days of index discharge while 45 (37%) had re-contact with the health system thereafter for non-seizure-related issues. Seven of 122 patients (6%) had a seizure-related ED visit or hospital readmission within 30 days of discharge. Twenty-eight (23%) had a seizure-related readmission or ED visit after 30 days. Of these 28, 4 patients had been to an ER within 7 days of EMU discharge. The majority of subsequent encounters with the healthcare system were through the ED (n = 38) as compared to hospital (n = 10) and EMU readmissions (n = 9). On bivariate statistical analysis, charity or self-pay insurance status (p < 0.01), homelessness (p < 0.01), emergent EMU admission on index admission (p < 0.01), history of a psychiatric diagnosis (p < 0.02), and ED encounters 12 months prior to admission (p < 0.01) were significantly associated with readmission; however, on multivariate analysis only charity insurance status was a significant predictor. CONCLUSIONS: In this study of readmissions and ED visits after discharge with a diagnosis of PNES at a safety net hospital, we found a seizure-related readmission rate of approximately 6% in 30 days and 23% thereafter with the majority of re-contact with the hospital being in the ED. On multi-variate analysis insurance status was a significant factor associated with readmission and ED visits. Our future research directions include examining referrals and treatment completion at the hospital's PNES clinic as well as creating a risk score to better identify patients with PNES at risk of readmission.

Back to Basics: Care of the Stereotactic EEG Implanted Patient.

PURPOSE: Stereotactic EEG (SEEG) is gaining increasing popularity in the United States. Patients undergoing SEEG have unique challenges, and their needs are different compared with noninvasive cases. We aim to describe the medical, nursing, and other institutional practices of SEEG evaluations among tertiary referral (level IV) epilepsy centers accredited by the National Association of Epilepsy Centers. METHODS: We analyzed data obtained from a Research Electronic Data Capture (REDCap) survey we formulated and distributed to directors of all level IV epilepsy centers listed by the National Association of Epilepsy Center. Most questions were addressed to the adult and pediatric SEEG programs separately. RESULTS: Among 199 epilepsy center directors invited to complete the survey, 90 (45%) responded. Eighty-three centers (92%) reported they perform SEEG evaluations. Of the 83 respondents, 56 perform SEEG in adult and 47 in pediatric patients. Twenty-two centers evaluate both pediatric and adult subjects. The highest concordance of SEEG workflow was in (1) epilepsy monitoring unit stay duration (1-2 weeks, 79% adult and 85% pediatric programs), (2) use of sleep deprivation (94% both adult and pediatric) and photic stimulation (79% adult and 70% pediatric) for seizure activation, (3) performing electrical cortical stimulation at the end of SEEG evaluation after spontaneous seizures are captured (84% adult and 88% pediatric), and (4) daily head-wrap inspection (76% adult and 80% pediatric). Significant intercenter variabilities were noted in the other aspects of SEEG workflow. CONCLUSIONS: Results showed significant variability in SEEG workflow across polled centers. Prospective, multicenter protocols will help the future development and harmonization of optimal practice patterns.

Real-Time Seizure Detection Using Behind-the-Ear Wearable System.

INTRODUCTION: This study examines the usability and comfort of a behind-the-ear seizure detection device called brain seizure detection (BrainSD) that captures ictal electroencephalogram (EEG) data using four scalp electrodes. METHODS: This is a feasibility study. Thirty-two patients admitted to a level 4 Epilepsy Monitoring Unit were enrolled. The subjects wore BrainSD and the standard 21-channel video-EEG simultaneously. Epileptologists analyzed the EEG signals collected by BrainSD and validated it using video-EEG data to confirm its accuracy. A poststudy survey was completed by each participant to evaluate the comfort and usability of the device. In addition, a focus group of UT Southwestern epileptologists was held to discuss the features they would like to see in a home EEG-based seizure detection device such as BrainSD. RESULTS: In total, BrainSD captured 11 of the 14 seizures that occurred while the device was being worn. All 11 seizures captured on BrainSD had focal onset, with three becoming bilateral tonic-clonic and one seizure being of subclinical status. The device was worn for an average of 41 hours. The poststudy survey showed that most users found the device comfortable, easy-to-use, and stated they would be interested in using BrainSD. Epileptologists in the focus group expressed a similar interest in BrainSD. CONCLUSIONS: Brain seizure detection is able to detect EEG signals using four behind-the-ear electrodes. Its comfort, ease-of-use, and ability to detect numerous types of seizures make BrainSD an acceptable at-home EEG detection device from both the patient and provider perspective.

Stereo-electroencephalographic seizure localization in patients with mesial temporal sclerosis: A single center experience.

Objective: Epilepsy patients with mesial temporal sclerosis (MTS) on imaging who are drug-resistant usually undergo epilepsy surgery without previous invasive evaluation. However, up to one-third of patients are not seizure-free after surgery. Prior studies have identified risk factors for surgical failure, but it is unclear if they are associated with bilateral or discordant seizure onset. Methods: In this retrospective case series, we identified 17 epilepsy patients who had MRI-confirmed MTS but received invasive stereo-EEG (SEEG) evaluation before definitive intervention. We analyzed their presurgical risk factors in relation to SEEG seizure onset localization and MRI/SEEG concordance. Results: SEEG ictal onset was concordant with MTS localization (i.e. seizures started only from the hippocampus with MTS) in 5 out of 13 patients with unilateral MTS (UMTS) and in 3 out of 4 patients with bilateral MTS.No statistically significant association regarding concordance of SEEG ictal onset and MTS location was found in patients with such risk factors as a history of non-mesial temporal aura, frequent focal to bilateral tonic-clonic seizures, prior viral brain infection, or family history of epilepsy. Nine out of 13 UMTS patients had resective surgery only, 5 out of 9 (56 %) have Engel class I outcome at most recent follow-up (median 46.5 months, range 22-91 months). In Engel class I cohort, the SEEG ictal onset was concordant with MTS location in 3 out of 5 patients, and 2 patients had ipsilateral temporal neocortical ictal onset. Conclusions: Our findings suggest that patients with MTS might have discordant SEEG ictal onset (in 61.5% patients with UMTS in presented cohort), which may explain poor surgical outcome after destructive surgery in these cases. Significance: Although no statistically significant association was found in this under-powered study, these findings could be potentially valuable for future meta-analyses.

Stereo-EEG Evaluation and Surgical Treatment in Patients With Drug-Resistant Focal Epilepsy Associated With Nodular Heterotopia.

PURPOSE: Nodular heterotopia (NH) is a common cause of drug-resistant epilepsy. Only limited studies detail the treatment of NH with laser interstitial thermal therapy and none analyze the relation between epileptogenicity and NH location. METHODS: We retrospectively studied nine patients with drug-resistant epilepsy and NH who underwent stereoelectroencephalography and subsequent epilepsy surgery. Nodular heterotopia in the frontal lobes or along the bodies of the lateral ventricles was classified as anterior NH. Nodular heterotopia in the trigones, temporal or occipital horns, or temporal lobes was classified as posterior NH. Nodular heterotopia in both anterior and posterior locations was classified as diffuse NH. Interictal and ictal stereoelectroencephalography were analyzed, and patients were followed postoperatively to assess outcomes. RESULTS: Of the six patients who underwent nine laser interstitial thermal therapy procedures either in isolation or in combination with other surgical therapies, four patients were Engel Ia, one was Engel IIb, and one was Engel IIIa, with an average follow-up of 22.8 months. All patients with posterior NH had interictal epileptiform abnormalities and seizures originating from the posterior NH. None of the patients with anterior NH had epileptiform activity recorded from their NH. CONCLUSION: Laser interstitial thermal therapy alone or in combination with other surgical therapies is an effective treatment in those with drug-resistant epilepsy because of NH, even in those with extensive NH and broad seizure onset. We observed a trend suggesting that posterior NH are more likely to be epileptogenic compared with anterior NH and recommend that in patients with anterior NH, alternative epilepsy etiologies and stereoelectroencephalography implantation strategies be considered.

Epilepsy surgery in patient with monogenic epilepsy related to SCN8A mutation.

Epilepsy surgery is superior to prolonged medical therapy in patients with drug-resistant focal epilepsy, but reports on epilepsy surgery outcomes for patients with a genetic etiology are limited, especially in adults. This is the first documented report of a stereoelectroencephalography (SEEG) evaluation and resective surgery outcome in an adult patient with epilepsy related to SCN8A mutation. We describe a patient with epilepsy related to SCN8A mutation which was reported as a variant of uncertain significance at time of his pre-surgical evaluation and reclassified as likely pathogenic about 3 years after resective epilepsy surgery. Most of his pre-surgical evaluation results suggested right temporal lobe epilepsy, but few reported semiological symptoms, ictal SPECT, and neuropsychology results were discordant, and brain MRI was non-lesional. Therefore, SEEG was recommended; ultimately, seizures were localized to the right hippocampus. He was seizure-free for 1.5 years after right anterior temporal lobectomy, then reported three focal to bilateral tonic-clonic (FBTC) seizures in the subsequent 12 months (preoperatively, 6 focal impaired awareness seizures and 4-6 FBTC per year). This case demonstrates that epilepsy surgery reduced seizure burden in a patient with SCN8A-related epilepsy granting him short-term seizure freedom after resection, and then decreased seizure frequency after relapse compared to the preoperative baseline.

Pearls & Oy-sters: Two Cases of Stereotactic EEG-Proven Insular Epilepsy With Nonlocalizing Scalp EEG and Interesting Semiologies.

Insular epilepsy is a great mimicker and can be mistaken for seizures originating from other areas of the brain or as nonepileptic spells. The semiology of insular epilepsy can include, but is not limited to, auditory illusions, paresthesias, gastric rising, laryngeal constriction, and hyperkinetic movements. These arise from both the functions of the insula itself and its extensive connections with other regions of the brain. Noninvasive workup can be negative or nonlocalizing because of the insula's location deep within the lateral sulcus. Stereotactic EEG can therefore be an important tool in cases of insular epilepsy so that patients may be appropriately diagnosed and evaluated for potential surgical treatment. We present 2 cases of epilepsy with nonlocalizing scalp EEG and challenging semiologies, the workup undertaken to identify them as cases of insular epilepsy, and subsequent surgical treatments and outcomes.

Single center outcomes of intracranial evaluation and surgical intervention in the elderly population.

Objective: The object of this case series is to report the effectiveness and complication rates of presurgical evaluation and surgical treatment among elderly epilepsy patients in our clinic. Methods: We reviewed patients charts from 2016 to 2020 and identified patients over the age of 55 years of age who underwent intracranial EEG, resection, and device placement. We compared the complications and post-intervention outcomes of 14 different patients. Results: The mean age of patients was 63.6 ± 4.13 years, and 6 (42.9 %) patients were female. 8 (57.1 %) patients underwent intracranial evaluation; 6 patients underwent SEEG, and 2 patients underwent SDE placement. 5/11 (45 %) patients reached seizure freedom with at least one year follow-up. Discussion: Intracranial evaluation could play an important role in the success of surgical intervention in the elderly epilepsy population. Prospective, multicenter studies are needed to determine the ideal candidate for a safe and effective intracranial evaluation and resection.

Emergent Admissions to the Epilepsy Monitoring Unit in the Setting of COVID-19 Pandemic-related, State-mandated Restrictions: Clinical Decision Making and Outcomes.

Due to the coronavirus disease 2019 (COVID-19) pandemic, the state of Texas-limited elective procedures to conserve beds and personal protective equipment (PPE); therefore, between March 22 and May 18, 2020, admission to the epilepsy monitoring unit (EMU) was limited only to urgent and emergent cases. We evaluated clinical characteristics and outcomes of these patients who were admitted to the EMU. Nineteen patients were admitted (one patient twice) with average age of 36.26 years (11 female) and average length of stay 3 days (range: 2-9 days). At least one event was captured on continuous EEG (cEEG) and video monitoring in all 20 admissions (atypical in one). One patient had both epileptic (ES) and psychogenic non-epileptic seizures (PNES) while 10 had PNES and 9 had ES. In 8 of 9 patients with ES, medications were changed, while in 5 patients with PNES, anti-epileptic drugs (AED) were stopped; the remaining 5 were not on medications. Of the 14 patients who had seen an epileptologist pre-admission, 13 (or 93%) had their diagnosis confirmed by EMU stay; a statistically significant finding. While typically an elective admission, in the setting of the COVID-19 pandemic, urgent and emergent EMU admissions were required for increased seizure or event frequency. In the vast majority of patients (13 of 19), admission lead to medication changes to either better control seizures or to change therapeutics as appropriate when PNES was identified.

Non-lesional mesial temporal lobe epilepsy requires bilateral invasive evaluation.

PURPOSE: Mesial temporal lobe epilepsy (MTLE) usually responds well to surgical treatment, although in non-lesional cases up to 50% of patients experience seizure relapse. The possibility of bilateral independent seizure onset should be considered as a reason for epilepsy surgery failure. METHODS: In a cohort of 177 patients who underwent invasive presurgical evaluation with stereo-tactically placed electrodes in two level four epilepsy centers, 29 had non-lesional MTLE. Invasive evaluation results are described. RESULTS: Among 29 patients with non-lesional MRI and mesial temporal lobe seizure onset recorded during stereo-EEG (SEEG) evaluation, four patients with unilateral preimplantation hypothesis had independent bilateral mesial temporal seizures on SEEG despite of unilateral non-invasive evaluation data. Three of these patients were treated with bitemporal responsive neurostimulator system (RNS). Independent bilateral mesial temporal seizures have been confirmed on RNS ECoG (electrocorticography). The fourth patient underwent right anterior temporal lobectomy. CONCLUSION: We propose that patients with non-lesional mesial temporal lobe epilepsy would benefit from bilateral invasive evaluation of mesial temporal structures to predict those patients who would be at most risk for surgical failure. Neurostimulaiton could be an initial treatment option for patients with independent bitemporal seizure onset.

Magnetoencephalography and ictal SPECT in patients with failed epilepsy surgery.

OBJECTIVE: Selected patients with intractable focal epilepsy who have failed a previous epilepsy surgery can become seizure-free with reoperation. Preoperative evaluation is exceedingly challenging in this cohort. We aim to investigate the diagnostic value of two noninvasive approaches, magnetoencephalography (MEG) and ictal single-photon emission computed tomography (SPECT), in patients with failed epilepsy surgery. METHODS: We retrospectively included a consecutive cohort of patients who failed prior resective epilepsy surgery, underwent re-evaluation including MEG and ictal SPECT, and had another surgery after the re-evaluation. The relationship between resection and localization from each test was determined, and their association with seizure outcomes was analyzed. RESULTS: A total of 46 patients were included; 21 (46%) were seizure-free at 1-year followup after reoperation. Twenty-seven (58%) had a positive MEG and 31 (67%) had a positive ictal SPECT. The resection of MEG foci was significantly associated with seizure-free outcome (p = 0.002). Overlap of ictal SPECT hyperperfusion zones with resection was significantly associated with seizure-free outcome in the subgroup of patients with injection time ≤20 seconds(p = 0.03), but did not show significant association in the overall cohort (p = 0.46) although all injections were ictal. Patients whose MEG and ictal SPECT were concordant on a sublobar level had a significantly higher chance of seizure freedom (p = 0.05). CONCLUSIONS: MEG alone achieved successful localization in patients with failed epilepsy surgery with a statistical significance. Only ictal SPECT with early injection (≤20 seconds) had good localization value. Sublobar concordance between both tests was significantly associated with seizure freedom. SPECT can provide essential information in MEG-negative cases and vice versa. SIGNIFICANCE: Our results emphasize the importance of considering a multimodal presurgical evaluation including MEG and SPECT in all patients with a previous failed epilepsy surgery.

Stereo-Encephalography Versus Subdural Electrodes for Seizure Localization.

In today's practice, epileptologists and neurosurgeons have several options for seizure localization with intracranial electrodes during phase II evaluations. Traditionally, centers in North America have used subdural electrode grids (SDE or SDG) for intracranial seizure localization. However, improvements in technology led to the popularization of stereo-encephalography (SEEG) using depth electrodes. Epilepsy surgery centers highest in volume now offer both SDE and SEEG for seizure localization. This article provides a general guide for considering SEEG versus SDE for intracranial seizure localization based on our experience with both. Several paradigmatic cases are used illustrate the advantages and disadvantages of the different approaches.

Aicardi syndrome: epilepsy surgery as a palliative treatment option for selected patients and pathological findings.

The optimal treatment for medically refractory epilepsy in Aicardi syndrome (AS) is still unclear. Palliative surgical treatment, including vagus nerve stimulation and corpus callosotomy, has therefore been used. There is limited data on the role of resective epilepsy surgery as a treatment choice in patients with AS. Here, we describe the seizures, anatomo-pathological findings, and neurodevelopmental outcome of palliative epilepsy surgery in two children with AS who had resective epilepsy surgery at the Cleveland Clinic. The related literature is also reviewed. Case 1 had a left functional hemispherectomy and was free of seizures and hypsarrhythmia for six months after surgery. Her gross motor skills improved after surgery. Outcome at 43 months was 1-3 isolated spasms per day. Case 2 had a right fronto-parietal lobectomy. Her seizures improved in frequency and severity, but remained daily after epilepsy surgery. Neurodevelopment changes included improved alertness and recognition of caregivers. This patient died 21 months after epilepsy surgery of unclear causes. Surgical pathology in both cases showed focal cortical dysplasia associated with other findings, such as nodular heterotopia and polymicrogyria. Epilepsy surgery could be an alternative palliative treatment choice in selective cases of AS, but studies on a larger patient cohort are needed to identify the possible role of surgery in children with AS. The complexity of the pathological findings may offer an explanation for the severity of seizures in AS.